Battery/discriminating method, drycell battery pack, and electronic device

ABSTRACT

A battery discriminating method discriminates between smart battery packs and dry cell battery packs with a simple structure. A dry cell battery pack is composed of a case for storing a plurality of dry batteries connected in series, positive and negative electrodes which are provided in the case and connected to the series-connected dry batteries, and a resistance element of which one end is connected to the series-connected dry batteries and the other end is connected to a terminal provided in the case. A predetermined voltage is supplied to a terminal for discriminating the battery of a battery pack via a resistor, and the voltage value of this terminal detected to discriminate the type of the battery pack according to the detected voltage value.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a battery discriminating method, dry cellbattery pack, and electronic device, and more particularly, isapplicable to a dry cell battery pack for supplying a direct current andan electronic device in which both this dry cell battery pack and abattery pack can be used.

2. Description of the Related Art

Nowadays, high-capacity battery packs storing battery cells such as aplurality of lithium-ion battery cells has been used to supply a directcurrent to electronic devices such as a portable personal computer,video camera, and portable telephone.

Such battery packs contain chargeable battery cells, thus they are veryexpensive. However, as electronic devices become smaller in size andachieve a larger saving in power consumption, inexpensive dry cellbatteries come to be used in electronic devices which could be used onlywith charge-battery packs, hitherto. Battery packs become unusable ifthe battery becomes empty when used at the place he has gone to, becausethey have a charging system. Accordingly, the necessity to carry aplurality of charged battery packs occurs.

However, to buy a plurality of charged battery packs is economicallyburdensome on the user because battery packs are expensive as describedabove. If electronic devices can be used with dry batteries, it is veryconvenient for the user since the user can buy dry batteries at a nearbystore or the like and can start the use of an electronic device again.

In battery packs and dry cell battery packs usable in the sameelectronic devices, the structure of electrodes is the same naturally.Thus in this state, it is feared that a dry cell battery pack is fittedin a charger. Therefore, it is needed that a battery pack is made so asnot to fit in a charger, or it is needed to prevent the charging that acharger discriminates that it is a dry cell battery pack if a dry cellbattery pack is fitted in a charger. It is more convenient that dry cellbattery packs and battery packs are discriminated not only by chargersbut also in accordance with the specifications of electronic devices.

Heretofore, to discriminate battery packs from dry cell battery packs,for example, a concave part is provided on the side of a battery packfacing an electronic device but the concave part provided on the batterypack is not provided on the side of a dry cell battery pack facing theelectronic device. Further, a push switch which can move up and down bymeans of a spring or the like is provided on a face for attaching apower source of the electronic device. When the battery pack is fittedto the electronic device, the push switch provided on the power sourceattaching part is connected with the concave part, so that this pushswitch is not pushed down. A microcomputer in the electronic devicedetects this state and determines that a battery pack is fitted thereto.On the other hand, when a dry cell battery pack is fitted to theelectronic device, the push switch provided on the power source fittingpart is pushed down by a flat part of a dry battery cell. Themicrocomputer in the electronic device detects this state and determinesthat a dry cell battery pack is fitted thereto. As the above, a pluralsets of a push switch and a concave part are provided so that types ofdiscriminatable power sources can be increased.

Recently, since microcomputers are low-cost, smart battery packs inwhich a microcomputer is built in a battery pack to performcommunication with an electronic device appears. By using such smartbattery packs, a remained capacity of the battery can be calculatedcorrectly, and further, the quantity of charge is controlled to detectthe life of battery and transmit it to an electronic device. Theelectronic device displays it on a display unit such as a liquid crystalpanel of the electronic device.

By the way, the use of dry cell battery packs in the electronic deviceswhich can use smart battery packs has been also considered so thatelectronic devices which can use both dry cell battery packs and batterypacks comes to entry as described above. However, if a microcomputer isbuilt in dry cell battery packs similar to smart battery packs, itbecomes expensive; as a result, low-cost performance of dry cell batterypacks, which is one of the advantages, cannot be realized.

Moreover, in the above-described method of discriminating betweenbattery packs and dry cell battery packs, types of those packs arediscriminated in the external form of battery packs and dry cell batterypacks, therefore, it is needed that a push switch described above isprovided on the battery fitting part of an electronic device; it sufferslimitation on planning of electronic devices. Also, in the case wherethe reduction of the size of electronic devices is realized by providinga plurality of push switches to discriminate between plural types ofbatteries, a space between switches become narrow, so that errordiscrimination is likely to occur.

SUMMARY OF THE INVENTION

In view of the foregoing, an object of this invention is to provide abattery discriminating method in which the type of battery can bediscriminated correctly with a simple structure, a dry cell battery packwhich realizes low-cost performance, and an electronic device which canbe reduced in size for discriminating the type of the battery.

The foregoing object and other objects of the invention have beenachieved by the provision of a battery discriminating method, wherein abattery pack which has at least, first and second terminalscorresponding to positive and negative electrodes and a third terminal,a predetermined voltage is supplied to the third terminal via aresistor, and the voltage value of the third terminal is detected todiscriminate the type of the battery pack according to the detectedvoltage value.

Further, a dry cell battery pack is composed of a case for storing aplurality of dry batteries connected in series, positive and negativeelectrodes or terminals which are provided in this case and connected tothe poles of the series-connected dry cell batteries, and a resistanceelement of which one end is connected to a predetermined connectingpoint of the series-connected dry cell batteries and the other end isconnected to a terminal provided in the case.

Furthermore, an electronic device according to the present invention canbe driven by plural types of battery packs each of which has at least,first and second terminals corresponding to positive and negativeelectrodes and a third terminal. The electronic device is composed of ameans for supplying a predetermined voltage to the third terminal via aresistor, a means for detecting the voltage value of the third terminal,and a means for comparing the detected voltage value with apredetermined reference voltage, thereby, the electronic devicediscriminates the type of the battery pack according to the comparisonresult.

The nature, principle and utility of the invention will become moreapparent from the following detailed description when read inconjunction with the accompanying drawings in which like parts aredesignated by like reference numerals or characters.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is an external view showing a general structure according to theembodiment;

FIG. 2 is an external view showing the outline of a smart battery packand a dry cell battery pack;

FIG. 3 is a block diagram showing the internal structure of the smartbattery pack and an electronic device;

FIG. 4 is a block diagram showing the internal structure of the dry cellbattery pack and the electronic device;

FIG. 5 is a block diagram showing the internal structure of the batterypack and the electronic device; and

FIG. 6 is a flowchart showing the process of a power-sourcediscriminating method according to the embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENT

Preferred embodiments of this invention will be described with referenceto the accompanying drawings:

Note that, the following embodiment will be described in the case ofusing a video camera as an electronic device, however, the presentinvention is not limited to this.

In FIG. 1, a reference numeral 10 denotes a dry cell battery pack inwhich a plurality of dry cell batteries are stored, a reference numeral20 denotes a video camera in which a battery pack is to be inserted intothe case from the outside, a reference numeral 30 is a smart batterypack in which a plurality of charge-battery cells and a microcomputerare contained, and a reference numeral 40 is a conventional batterypack.

In the dry cell battery pack 10, a positive electrode or terminal 11 anda negative electrode or terminal 12 are provided, so that when the drycell battery pack 10 is fitted to the video camera 20, the terminals 11and 12 of the dry cell battery pack are connected to electrodes orterminals 21 and 22 which are provided in a battery fitting part of thevideo camera 20. In this way, the dry cell battery pack 10 can supply adirect current to the video camera 20 through the terminals 11, 12, andthe terminals 21, 22.

In addition, in the dry cell battery pack 10, a battery discriminatingterminal 13 is provided, so that when the dry cell battery pack 10 isfitted to the video camera 20, the terminal 13 is connected to aterminal 23 of the battery fitting part. This terminal 13 is providedfor battery discrimination.

In the smart battery pack 30, a positive electrode or terminal 31 and anegative electrode or terminal 32 are provided, so that when the smartbattery pack 30 is fitted to the video camera 20, the terminals 31 and32 of the smart battery pack are connected to the terminals 21 and 22,which are provided in the battery fitting part. In this way, the smartbattery pack 30 can supply a direct current to the video camera 20through the terminals 31, 32 and the terminals 21, 22.

In addition, in the smart battery pack 30, a battery discriminatingterminal 33 is provided, so that when the smart battery pack 30 isfitted to the video camera 20, the terminal 33 is connected to theterminal 23 of the battery fitting part. This terminal 33 is connectedto the microcomputer 35 contained in the smart battery pack 30 forcommunication to a microcomputer 25 contained in the video camera 20.

In the battery pack 40, a positive electrode or terminal 41 and anegative electrode or terminal 42 are provided, so that when the batterypack 40 is fitted to the video camera 20, the terminals 41 and 42 of thebattery pack 40 are connected to the terminals 21 and 22 provided in thebattery fitting part of the video camera 20. In this way, the batterypack 40 can supply a direct current to the video camera 20 through theterminals 41, 42, and the terminals 21, 22.

This battery pack 40 is one which has been used in conventional videocameras, and which has no terminal like the terminal 13 of the dry cellbattery pack 10 and the terminal 33 of the smart battery pack.

In the battery fitting part of the video camera 20, the terminals 21 and22 are provided, so that a direct current is supplied from any of thedry battery cell pack 10, the smart battery pack 30, and the batterypack 40. The terminal 23 provided in the battery fitting part is used asa discriminating terminal for discriminating that either battery of thedry cell battery pack 10 or the smart battery pack 30 has been fittedand also as a communication terminal between the microcomputer 35contained in the smart battery pack and the microcomputer 25 containedin the video camera 20. Note that, FIG. 1 shows an example in which thedry cell battery pack 10, the smart battery pack 30, and the batterypack 40 are fitted by way of inserting in the case of the video camera20, but it may be a type attaching to the video camera.

FIG. 2 is a perspective view showing the outside view of the dry cellbattery pack 10 and the smart battery pack 30. Here, it is describedassuming that the external structure of the cases of the dry cellbattery pack 10 and the smart battery pack 30 (hereinafter, they arecalled the battery pack 10 (30) lumping them together) are the same. Thebattery pack 10 (30) is composed of an upper case part 14 and a lowercase part 15. On the upper case part 14, a reverse-insertion preventinggroove 17 is provided. As shown in FIG. 1, in the video camera in whichthe battery pack 10 (30) is fitted by way of inserting in the case ofthe video camera 20, a reverse-insertion preventing rib 51 whichcorresponds to the reverse-insertion preventing groove 17 of the batterypack 10 (30) is provided. This combination of the reverse-insertionpreventing groove 17 and the reverse-insertion preventing rib 51prevents the battery pack 10 (30) from being inserted in the reversedirection.

In FIG. 2, connecting grooves 16a and 16b are provided on the side ofthe lower case part 15 of the battery pack 10 (30) and similarconnecting grooves 16c and 16d, which are not shown, are provided on theside at the back. If the battery pack 10 (30) is attached to theattach-type video camera, these connecting grooves are connected withconnecting projections which are provided in the battery fitting part ofthe video camera, and a locking projection of the battery fitting partof the video camera is connected with a locking concave part, which isnot shown, on the bottom of the battery pack 10 (30): thus the fittingstate is kept.

On the front in the insert direction of the lower case part 15 of thebattery pack 10 (30), the terminals 11 (31) and 12 (32) are provided atboth ends and the terminal 13 (33) is provided at the center. Note that,the external structure of the case of the conventional battery pack 40is the same except that the terminal 13 (33) is not provided therein.

In the embodiment shown in FIG. 1, to simplify the explanation, the drycell battery pack 10 and the smart battery pack 30 are made the same inthe external structure, however, those may be different in shape andsize.

However, at least, these must be the same: the structure of theterminals 11 (31) and 12 (32) of the lower case part 15 and the terminal13 (33) and the positional relation to keep the interchangecharacteristic between the battery pack 10 and the smart battery pack30. More specifically, in the case where the size of the dry cellbattery pack 10 and the smart battery pack 30 are changed, the size ofthe upper case part 14 should be changed as these are the same in thestructure of the terminals 11 (31) and 12 (32) of the lower case part 15and the terminal 13 (33). However, in the case where two battery packs10 (30) which are different in size as the above are fitted to a videocamera of the type of inserting the battery pack 10 (30) in the case, itis needed to consider the structure of a battery fitting part.

FIG. 3 shows the state where the smart battery pack 30 is fitted to thevideo camera 20. The smart battery pack 30 is composed of a plurality ofchargeable battery cells 36 which are connected between the terminals 31and 32, a microcomputer 35, and a power circuit 34 for themicrocomputer. The power circuit 34 generates operating voltage for themicrocomputer 35 from the terminal voltage of the battery cells 36 tosupply it to the microcomputer 35. The microcomputer 35 communicateswith an electronic device 20 via a terminal 33.

The video camera 20 is composed of a voltage regulator 24, amicrocomputer 25 for controlling the video camera 20, a field effecttransistor (FET) 26, a pull-up resistor RI having extremely-highresistance value, and a voltage-dividing resistor R2. The positiveterminal 31 of the smart battery pack 30 is connected to the terminal 21to provide constant voltage by the voltage regulator 24. The constantvoltage is supplied to a terminal 27a of the microcomputer 25. On theother hand, the negative terminal 32 of the smart battery pack 30 isconnected to a terminal 27d of the microcomputer 25 via the terminal 22.The microcomputer 25 inputs an input signal from the terminal 23 to adetecting-voltage input terminal 27b. One end of the FET 26 is connectedto the line between the terminal 22 and the terminal 27d, and the otherend is connected to the line between the terminal 23 and thedetecting-voltage input terminal 27b via the resistor R2. Furthermore, agate terminal of the FET 26 is connected to a communication outputterminal 27c of the microcomputer 25.

FIG. 4 shows the state where the dry cell battery pack 10 is fitted tothe video camera 20. The dry cell battery pack 10 is composed of aplurality of dry cells 14 which are connected in series between theterminals 11 and 12, and a voltage-dividing resistor R3. One end of thevoltage-dividing resistor R3 is connected to a positive pole of thefirst dry cell of those six dry cells, and the other end is connected toa battery discriminating terminal 13. An explanation of the structure ofthe video camera 20 is omitted because it is the same as that FIG. 3.Here, it is assumed that the voltage-dividing resistor R2 included inthe video camera 20 and the voltage-dividing resistor R3 included in thedry cell battery pack 10 are the same in resistance value to simplifythe description, but the present invention is not limited to this.

FIG. 5 shows the state where the battery pack 40 is fitted to the videocamera 20. The battery pack 40 is composed of a plurality of batterycells 43 which are connected in series between terminals 41 and 42.Nothing is connected to the terminal 23 of the video camera 20 becausethe battery pack 40 has no terminal for communication and batterydiscrimination.

According to the above structure, a discriminating method between thedry cell battery pack 10, the smart battery pack 30, and the batterypack 40 will be described accompanying with a flowchart shown in FIG. 6.The flowchart of FIG. 6 shows the operation of the microcomputer 25which is included in the video camera 20. First, the process is startedin step SP1 and whether the power is turned on is determined (step SP2).If power ON is determined, the communication output terminal 27c isturned to a logic "H" level (step SP3). If the communication outputterminal 27c is turned to the logic "H" level, the FET 26 is turned toan ON state. Here, in the case where the smart battery pack 30 is fittedto the video camera 20 (FIG. 3), the voltage value of the terminal 27bbecomes almost 0 [V]. On the contrary, in the case where the dry cellbattery pack 10 is fitted to the video camera 20 (FIG. 4), the voltagevalue of the terminal 27b becomes almost half of the terminal voltage ofdry cell battery (because the resistance values of the voltage-dividingresistors R2 and R3 are equal). Further, in the case where the batterypack 40 is fitted to the video camera (FIG. 5), the voltage value of theterminal 27b becomes almost 0 [V] because the resistance value of thepull-up resistor R1 is much larger than that of the voltage-dividingresistor R2.

The microcomputer 25 of the video camera 20 executes analog-to-digital(A/D) conversion function mounted therein to detect the voltage value ofthe terminal 27b (step SP4). Then the detected voltage value istemporarily stored as detection data D1 (step SP5).

Next, the microcomputer 25 outputs an output of a logic "L" level to thecommunication output terminal 27c (step SP6). If the communicationoutput terminal 27c is tuned to the logic "L" level, the FET 26 isturned to an OFF state. In the case where the smart battery pack 30 isfitted to the video camera 20 (FIG. 3), the voltage of the terminal 27bbecomes the output voltage (about 3.2 [V]) of the voltage regulator 24due to the pull-up resistor R1. On the contrary, in the case where thedry cell battery pack 10 is fitted to the video camera 20 (FIG. 4), avoltage of the terminal 27b becomes the voltage of a terminal voltage ofa dry cell battery because a resistance of the pull-up resistor R1 isvery large. Furthermore, in the case where the battery pack 40 is fittedto the video camera 20 (FIG. 5), a voltage of the terminal 27b becomesthe output voltage (about 3.2 [V]) of the voltage regulator 24 due tothe pull-up resistor R1.

The microcomputer 25 of the video camera 20 executes A/D conversionfunction mounted therein to detect a voltage value of the terminal 27b(step SP7). Then the detected voltage value is temporarily stored asdetection data D2 (step SP8).

Next, the microcomputer 25 performs comparison of whether the storeddetection data D2 is less than 2 [V] or not (step SP9). In the casewhere the dry cell battery pack 10 is fitted (FIG. 4), it proceeds tostep SP10 since the detection data D2 becomes the terminal voltage(about 1.5 [V]) of a piece of dry cell battery. The microcomputer 25discriminates whether the detection data D2 is double of the detectiondata D1 or not (step SP10). If an affirmative result is obtained, it isdetermined that a dry cell battery pack is fitted (step SP11). If noaffirmative result is obtained, it is determined that it is not a drycell battery pack (step SP12). On the other hand, in the case where thesmart battery pack 30 or the battery pack 40 is fitted as determined instep SP9 (FIGS. 3 and 5), the detection data D2 becomes the outputvoltage (about 3.2 [V]) of the voltage regulator 24 as described above,and as a result, it is determined that it is not the dry cell batterypack 10 (step SP12). If it is determined that it is not the dry cellbattery pack 10 (step SP12), that is, in the case where the smartbattery pack 30 is fitted, a communication is started (step SP13). Andit is checked whether a normal communication can be performed or not(step SP14). If able to perform a normal communication, it is determinedthat it is the smart battery pack 30 (step SP15) and then the aboveprocess is terminated (step SP16). On the contrary, if a normalcommunication cannot be performed, it is determined that it is thebattery pack 40 (step SP17).

As the above, it is so arranged as to perform discrimination between thedry cell battery pack 10 and the smart battery pack 30 by using thecommunication terminal 13 (33) for performing a communication betweenthe smart battery pack 30 and the electronic device so that it can beomitted to provide a particular structure such as a push switch as aconventional one, thus limitation on electronic device design can bereduced.

Also, the embodiment can discriminate electrically between the dry cellbattery pack 10 and the smart battery pack 30 without using themechanical structure such as a push switch in a battery fitting part ofthe electronic device so that error-determination can be prevented.

Furthermore, the embodiment is able to structure the dry cell batterypack 10 with a simple structure which is low-impedance only addingresistor R3, thereby, low-cost can be realized.

Note, that the present invention is not limited to the number of thecells 14 which are contained in the dry cell battery pack 10 and thenumber of battery cells 36 which are contained in the smart battery pack30. Further, the aforementioned embodiments, are described withreference to the video camera 20 as an example of the electronic device;the present invention, however, is not limited to this but can also beused in a portable telephone, a portable personal computer, or the like.

As described above, according to a battery discriminating method of thepresent invention, in a plural type of battery packs each of which hasat least, first and second terminals being positive and negativeterminals and a third terminal, a predetermined voltage is supplied tothe third terminal via a resistor, and the voltage value of the thirdterminal is detected to discriminate the type of the battery packaccording to the detected voltage value; thereby, the battery can bediscriminated with a simple structure. Further, it has no mechanicalstructure so that limitations on planning of electronic devices can bereduced. Moreover, even in the case where reduction of the size ofelectronic devices is aimed, discrimination error does not occurdifferentially from the case where a push switch is utilized.

Further, a dry cell battery pack according to the present invention iscomposed of a case for storing a plurality of dry batteries connected inseries, positive and negative terminals which are provided in the caseand connected to the poles of the series-connected dry batteries, and aresistance element of which one end is connected to a predeterminedconnecting point of the series-connected dry batteries and the other endis connected to a terminal provided in the case. Thereby, in a dry cellbattery pack which is interchangeable with a smart battery pack, onlyone low-impedance resistance element is increased, thus the cost can belowered.

Moreover, an electronic device according to the present inventioncomprises: in a plural type of battery packs having at least, first andsecond terminals corresponding to positive and negative electrodes and athird terminal, a means for supplying a predetermined voltage to thethird terminal via a resistor; a means for detecting the voltage valueof the third terminal; and a means for comparing the detected voltagevalue with a predetermined reference voltage are provided. Theelectronic device discriminates the type of the battery pack accordingto the comparison result. In addition, the terminal for communicatingwith a smart battery pack is used as battery discrimination so that thetype of battery can be discriminated with a simple structure withoutincreasing the number of terminals.

While the invention has been described in connection with the preferredembodiments thereof, it will be obvious to those skilled in the art thatvarious changes and modifications may be aimed, and therefore, theappended claims cover all such changes and modifications falling withinthe true spirit and scope of the invention.

What is claimed is:
 1. A battery discriminating method fordiscriminating a battery pack having first, second and third terminalsand a plurality of dry battery cells, said first and second terminalscorresponding to positive and negative electrodes of said battery pack,respectively, and said third terminal being connected via a firstresistor to an electric connecting point between cells, said methodcomprising:connecting a second resistor between the third terminal andthe second terminal; detecting a voltage on the third terminal at saidthird terminal resulting from the connected resistor; and determining atype of said battery pack based on the detected voltage value.
 2. Thebattery discriminating method according to claim 1, wherein the detectedvoltage value is approximately equal to a portion of a voltage valuethat is generated by said battery pack such that the type of saidbattery pack is determined to be a dry cell battery pack comprised of aplurality of series-connected battery cells.
 3. The batterydiscriminating method according to claim 2, wherein said portion of thegenerated voltage value is approximately equal to another voltage valuethat is generated by a battery cell in said plurality ofseries-connected battery cells.
 4. The battery discriminating methodaccording to claim 1, wherein the detected voltage value isapproximately equal to a voltage value that is output by a voltageregulator located in a device receiving power from said battery packsuch that the type of said battery pack is determined to be a non-drycell battery pack.
 5. The battery discriminating method according toclaim 4, further comprising transmitting communication information tothe determined non-dry cell battery pack such that the non-dry cellbattery pack is determined to be a microprocessor-based battery packwhen a response to the transmitted communication information isreceived.